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Date: Thu, 3 Aug 2017 21:33:27 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emlot.net, Florian Fainelli <f.fainelli@...il.com>,
Andrew Lunn <andrew@...n.ch>,
Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
"David S. Miller" <davem@...emloft.net>,
linux-kernel@...r.kernel.org (open list)
Subject: [PATCH net-next] net: dsa: User per-cpu 64-bit statistics
During testing with a background iperf pushing 1Gbit/sec worth of
traffic and having both ifconfig and ethtool collect statistics, we
could see quite frequent deadlocks. Convert the often accessed DSA slave
network devices statistics to per-cpu 64-bit statistics to remove these
deadlocks and provide fast efficient statistics updates.
Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
net/dsa/dsa.c | 10 +++++---
net/dsa/dsa_priv.h | 2 +-
net/dsa/slave.c | 72 +++++++++++++++++++++++++++++++++++++++---------------
3 files changed, 59 insertions(+), 25 deletions(-)
diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 0ba842c08dd3..a91e520e735f 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -190,6 +190,7 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
{
struct dsa_switch_tree *dst = dev->dsa_ptr;
struct sk_buff *nskb = NULL;
+ struct pcpu_sw_netstats *s;
struct dsa_slave_priv *p;
if (unlikely(dst == NULL)) {
@@ -213,10 +214,11 @@ static int dsa_switch_rcv(struct sk_buff *skb, struct net_device *dev,
skb->pkt_type = PACKET_HOST;
skb->protocol = eth_type_trans(skb, skb->dev);
- u64_stats_update_begin(&p->stats64.syncp);
- p->stats64.rx_packets++;
- p->stats64.rx_bytes += skb->len;
- u64_stats_update_end(&p->stats64.syncp);
+ s = this_cpu_ptr(p->stats64);
+ u64_stats_update_begin(&s->syncp);
+ s->rx_packets++;
+ s->rx_bytes += skb->len;
+ u64_stats_update_end(&s->syncp);
netif_receive_skb(skb);
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 7aa0656296c2..306cff229def 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -77,7 +77,7 @@ struct dsa_slave_priv {
struct sk_buff * (*xmit)(struct sk_buff *skb,
struct net_device *dev);
- struct pcpu_sw_netstats stats64;
+ struct pcpu_sw_netstats *stats64;
/* DSA port data, such as switch, port index, etc. */
struct dsa_port *dp;
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index e196562035b1..605444ced06c 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -352,12 +352,14 @@ static inline netdev_tx_t dsa_netpoll_send_skb(struct dsa_slave_priv *p,
static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct dsa_slave_priv *p = netdev_priv(dev);
+ struct pcpu_sw_netstats *s;
struct sk_buff *nskb;
- u64_stats_update_begin(&p->stats64.syncp);
- p->stats64.tx_packets++;
- p->stats64.tx_bytes += skb->len;
- u64_stats_update_end(&p->stats64.syncp);
+ s = this_cpu_ptr(p->stats64);
+ u64_stats_update_begin(&s->syncp);
+ s->tx_packets++;
+ s->tx_bytes += skb->len;
+ u64_stats_update_end(&s->syncp);
/* Transmit function may have to reallocate the original SKB,
* in which case it must have freed it. Only free it here on error.
@@ -596,15 +598,26 @@ static void dsa_slave_get_ethtool_stats(struct net_device *dev,
{
struct dsa_slave_priv *p = netdev_priv(dev);
struct dsa_switch *ds = p->dp->ds;
+ struct pcpu_sw_netstats *s;
unsigned int start;
-
- do {
- start = u64_stats_fetch_begin_irq(&p->stats64.syncp);
- data[0] = p->stats64.tx_packets;
- data[1] = p->stats64.tx_bytes;
- data[2] = p->stats64.rx_packets;
- data[3] = p->stats64.rx_bytes;
- } while (u64_stats_fetch_retry_irq(&p->stats64.syncp, start));
+ int i;
+
+ for_each_possible_cpu(i) {
+ u64 tx_packets, tx_bytes, rx_packets, rx_bytes;
+
+ s = per_cpu_ptr(p->stats64, i);
+ do {
+ start = u64_stats_fetch_begin_irq(&s->syncp);
+ tx_packets = s->tx_packets;
+ tx_bytes = s->tx_bytes;
+ rx_packets = s->rx_packets;
+ rx_bytes = s->rx_bytes;
+ } while (u64_stats_fetch_retry_irq(&s->syncp, start));
+ data[0] += tx_packets;
+ data[1] += tx_bytes;
+ data[2] += rx_packets;
+ data[3] += rx_bytes;
+ }
if (ds->ops->get_ethtool_stats)
ds->ops->get_ethtool_stats(ds, p->dp->index, data + 4);
}
@@ -879,16 +892,28 @@ static void dsa_slave_get_stats64(struct net_device *dev,
struct rtnl_link_stats64 *stats)
{
struct dsa_slave_priv *p = netdev_priv(dev);
+ struct pcpu_sw_netstats *s;
unsigned int start;
+ int i;
netdev_stats_to_stats64(stats, &dev->stats);
- do {
- start = u64_stats_fetch_begin_irq(&p->stats64.syncp);
- stats->tx_packets = p->stats64.tx_packets;
- stats->tx_bytes = p->stats64.tx_bytes;
- stats->rx_packets = p->stats64.rx_packets;
- stats->rx_bytes = p->stats64.rx_bytes;
- } while (u64_stats_fetch_retry_irq(&p->stats64.syncp, start));
+ for_each_possible_cpu(i) {
+ u64 tx_packets, tx_bytes, rx_packets, rx_bytes;
+
+ s = per_cpu_ptr(p->stats64, i);
+ do {
+ start = u64_stats_fetch_begin_irq(&s->syncp);
+ tx_packets = s->tx_packets;
+ tx_bytes = s->tx_bytes;
+ rx_packets = s->rx_packets;
+ rx_bytes = s->rx_bytes;
+ } while (u64_stats_fetch_retry_irq(&s->syncp, start));
+
+ stats->tx_packets += tx_packets;
+ stats->tx_bytes += tx_bytes;
+ stats->rx_packets += rx_packets;
+ stats->rx_bytes += rx_bytes;
+ }
}
void dsa_cpu_port_ethtool_init(struct ethtool_ops *ops)
@@ -1202,7 +1227,11 @@ int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
slave_dev->vlan_features = master->vlan_features;
p = netdev_priv(slave_dev);
- u64_stats_init(&p->stats64.syncp);
+ p->stats64 = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
+ if (!p->stats64) {
+ free_netdev(slave_dev);
+ return -ENOMEM;
+ }
p->dp = &ds->ports[port];
INIT_LIST_HEAD(&p->mall_tc_list);
p->xmit = dst->tag_ops->xmit;
@@ -1217,6 +1246,7 @@ int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
netdev_err(master, "error %d registering interface %s\n",
ret, slave_dev->name);
ds->ports[port].netdev = NULL;
+ free_percpu(p->stats64);
free_netdev(slave_dev);
return ret;
}
@@ -1227,6 +1257,7 @@ int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
if (ret) {
netdev_err(master, "error %d setting up slave phy\n", ret);
unregister_netdev(slave_dev);
+ free_percpu(p->stats64);
free_netdev(slave_dev);
return ret;
}
@@ -1249,6 +1280,7 @@ void dsa_slave_destroy(struct net_device *slave_dev)
of_phy_deregister_fixed_link(port_dn);
}
unregister_netdev(slave_dev);
+ free_percpu(p->stats64);
free_netdev(slave_dev);
}
--
2.9.3
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